Statement I: If and enclosed separately in the same vessel exert pressures of 100 and 200 mm respect — States of Matter and Gaseous State Chemistry Question

Question

Statement I: If $H_2$ and $Cl_2$ enclosed separately in the same vessel exert pressures of 100 and 200 mm respectively, their mixture in the same vessel at the same temperature will exerts a pressure of 300 mm. Statement II: Dalton's law of partial pressures states that total pressure is the sum of partial pressures.